Broadband communication systems are known in the art. The main types include video oriented communication systems and data oriented communication systems. Video oriented communication systems were originally designed for television broadcast transmissions and today include modifications, which enable narrow-cast transmissions as well as data communications there through. Data oriented communication systems are used for a plurality of data and multimedia applications. Conventionally, downstream channels (from the cable service operator to the end user) are used to carry either only IP packets (using for example) or only native MPEG programs over MPEG transport. This requires the cable operator to perform fixed allocation of downstream resources for different services, which limits the resource usage efficiency, especially for the downstream bandwidth.
Cable Modem Termination Systems (CMTS) are known in the art. Such systems are installed in a cable head-end and are connected to a plurality (conventionally thousands) of Cable Modems (CM) via a Hybrid Fiber/Coaxial (HFC) Network. A conventional single CMTS board transmits downstream information on a single channel and receives upstream information from one or more (usually not more than 8) upstream channels. Upstream channels which are connected to a single CMTS board, can be received from many nodes (usually for areas which are characterized by a small number of cable modem users) or from a single node (usually for areas which are characterized by a large number of cable modem users).
The operation of a conventional CMTS is generally predefined, where the cable modem users are configured to utilize a specific CMTS downstream channel. Each CMTS downstream channel has specific associated upstream channels. The CMTS board uses its associated downstream channel, to provide upstream channels and time slot information to the CMs on which they can transmit information back to the head-end, at any given time.
An article, “Multimedia Traffic Engineering for HFC Networks” by John T. Chapman from Cisco Systems (Nov. 29, 1999), discusses possible CMTS architectures contingent on penetration of CMs and broadband services.
Digital video and other media are typically transmitted in a compressed form, encapsulated in MPEG transport packets, which include information associating them to a specific stream. In general, digital transmission dramatically increases the potential network capacity. Ten to twenty digital video channels can be transmitted using a communication channel. Digital transmission further provides data transmission, using and MPEG transport.
New generations of set top boxes (STB's) includes two downstream tuners, one for video, one for data (e.g., these STBs are equipped with a cable modem). A WebTV set-top box manufactured and sold by Microsoft, allows the viewer to watch television programs while receiving data from a dedicated telephone line, using a dial-up modem connection.
The ability to transmit video and data combined together leads to a new class of applications, which are classified under Interactive TV (or sometime referred too as Enhanced TV). An Interactive TV application can be categorized into three main application types, each of which with different capabilities and technical challenges.
The first type includes personalized data applications transmitted to the set top box (STB) of the end user, such as WEB surfing and Email application on the TV screen. These applications use the STB processing capabilities, to bring basic Internet services to TV viewers with no use of computers.
The second type includes applications for transmitting narrow-cast video with data. The ability to combine data into a video on demand (VOD) session enable application that can let the user see additional information regarding the movie (e.g., actors names, directors and the like) by adding a link to the appropriate WEB site. Enabling such URL links provides a VOD system to add links to sites with products that are related to the movie and enables the user buy these products while watching the movie.
The third type includes application for transmitting narrow-cast data and broadcast video to same viewer, where, the narrow-cast data can be related or unrelated to the video program watched by the viewer.
For set-top devices that have two different paths one for video and one for data, these applications are very trivial to implement. (e.g., a WebTV box with telephone connection, or a digital STB with a DOCSIS cable modem inside).
This invention enabled the same 3 applications mentioned above on a digital STB which have only a single 6 MHz downstream tuner, where narrow-cast data is submitted In-Band (with the video programs either broadcast or on-demand). In this case, these applications are enabled by a unique headend device that can take all broadcast feeds, and grooms all program in a way that there is some bandwidth left on each channel for narrow-cast data delivery (e.g., 2-3M/bit sec in average). This device knows how to send the narrow-cast data to a specific viewer on the same channel the viewer's STB is currently tuned to. If the viewer's STB switched to a different channel, the headend device will know to redirect the viewer's narrow-cast data to the new channel.